1. Field of the Invention
The present invention relates to a catalytic apparatus for treating VOC (Volatile Organic Compound) vapor generated in an image forming apparatus using liquid toner for printing, and to discharge a harmless gas. The invention is also directed to an automatic VOC concentration control apparatus capable of controlling the concentration of the VOC vapor introduced into the catalytic apparatus not to exceed a predetermined value. The invention is further directed to an image forming apparatus having an automatic VOC concentration control apparatus.
2. Description of the Related Art
In general, an image forming apparatus using liquid toner for printing transfers an image developed by the liquid toner on a photoconductor to a print medium, and then feeds the image-transferred print medium through a high temperature/high pressure fixing apparatus, so that the transferred image is fixed to the print medium. In the process of fixing the image to the print medium, the organic compound of the liquid toner is vaporized by the high temperature, whereby VOC vapor is generated. Since such VOC is harmful, it shall not be discharged to the atmosphere as it is. Accordingly, a conventional wet type image forming apparatus has an apparatus 5 for turning VOC vapor generated in the image forming unit 3 into harmless gas and then discharging the harmless gas, as shown in FIG. 1. Typically, a VOC vapor treating apparatus in an image forming apparatus 1 is a catalytic apparatus. The catalytic apparatus decomposes VOC vapor into harmless gas that includes CO2, H2O or the like using catalyst such as platinum and discharges the harmless gas to the atmosphere.
Such a catalytic apparatus is designed on the basis of the maximum amount of VOC vapor which is expected to be generated in an image forming apparatus during use. However, since the maximum amount of VOC vapor is not always generated while printing, the efficiency of the catalyst is poor. That is, since it is necessary to use an amount of catalyst more than that capable of treating an average amount of VOC vapor expected to be generated, the capacity of the catalyst exceeds the normal requirements, thereby increasing the manufacturing costs of an image forming apparatus.
However, if such a catalytic apparatus is designed on the basis of an average amount of VOC vapor generated in order to save the costs, there is a risk that the catalytic apparatus may discharge VOC vapor to the atmosphere without fully treating the VOC vapor introduced into the catalytic apparatus when the generated VOC vapor exceeds the predetermined average amount. In addition, since the catalytic reaction for decomposing VOC is an exothermic reaction, the catalyst may overheat, degrade and lose its capability if it decomposes VOC vapor exceeding the design capacity of the catalytic apparatus. Therefore, there is a problem in that the life span of the catalyst is reduced.